JPH0523363B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention is a GPS navigation device for an automobile, in particular, a GPS navigation device for a vehicle, in particular, by processing the estimated current position of a vehicle and reception data of currently receivable satellite radio waves. Continuously displays position with good accuracy even when it is impossible to receive satellite radio waves at the same time
Regarding GPS navigation equipment.

(Prior art) A GPS positioning device usually receives three or more satellites at the same time, and receives pseudorange data including the time offset of the receiver between each satellite and the receiving point, and the position data of each receiving satellite. Devices are known that are configured to calculate and display the position of a point.

(Problems to be Solved by the Invention) However, there is a drawback that positioning cannot be performed when the number of receiving satellites is less than three due to the influence of shielding objects such as buildings in urban areas. In addition, as a solution to this problem, it is possible to display the estimated position using direction data and distance data from a compass and rangefinder while positioning is not possible, but the estimated position will accumulate position errors over time. Therefore, although continuous position display is possible, the position measurement error increases, and especially when the unreceivable period becomes long, this increase is significantly unsuitable for practical use.

(Means for Solving the Problems) In order to solve these drawbacks, the present invention aims to solve the problem that the reception of satellite radio waves is frequently interrupted due to the influence of shielding objects in urban areas. If reception is not possible, the direction data from the direction meter and distance meter will be collected from the time when reception becomes impossible, based on the immediately preceding satellite position data, while reception is interrupted. The pseudo satellite position data obtained using the vehicle's travel direction and travel distance obtained from the distance data and distance data, and the pseudo satellite position data obtained using the vehicle's travel distance, as well as the pseudo distance data immediately before reception interruption, are used to simulate the satellites currently receivable. The received data is a total of three received data, including the received data of other currently receivable satellites, to calculate the position, making it possible to perform continuous positioning without interruption, and to keep the azimuth data while the positioning is interrupted. GPS enables positioning with better accuracy than estimated position calculated from distance data
The purpose is to provide navigation equipment.

(Embodiment) FIG. 1 is a block diagram of an embodiment of the present invention, in which 1 is a GPS receiver, 2 is a pseudolite position calculator,
3 is a receiving position calculator, 4 is a position indicator, 5 is a car, 6 is a GPS receiver antenna, 7 is a magnetic compass, and 8 is a distance meter.

FIGS. 2a and 2b show the reception status of satellite radio waves and the positioning error curve (in other words, the positioning error curve), respectively. Regarding A in Figure a,
Of the reception status of satellite radio waves, the periods in which satellites 1, 2, and 3 are receivable are shown by solid lines, and the periods in which they are unreceivable are shown by dotted lines. The satellite position error during the unreceivable period is increasing as time passes, as shown in A of FIG. The average value of the positioning error according to the present invention based on the positioning error curves of these three satellites is shown in the solid line graph of the positioning error curve in FIG. 2b.

FIG. 3 is a diagram for explaining the present invention, in which 3
This shows how to receive radio waves from several satellites and perform positioning. At time t1, when the position of car ₉₁ is t1, radio waves from satellites 1, 2, and 3 can be received and positioning can be performed.
When the position of car 9 ₂ is at time t2, shielding object 1
0, the reception of radio waves from the satellite 3 is interrupted, making positioning impossible using conventional positioning methods. However, positioning becomes possible by calculating the position of the pseudosatellite 3 shown by the dotted line in the figure for explaining the present invention.

FIG. 4 is a diagram for explaining position measurement of a car according to the invention at time t2. That is, time t
Each of satellites 1 and 2 and a car 9 are centered on satellites 1 and 2 and pseudosatellites in 2.
a pseudorange and a pseudosatellite between the receiving position of ₂ ;
The measurement position is the center of a triangle surrounded by three circles whose radius is the pseudo-distance between the distance and the estimated position of the car ₉₃ . The pseudo distance between the pseudo satellite 3 and the estimated position 9 ₃ is the distance between the satellite 3 and the car 9 ₁ measured at time t1.
is equivalent to the pseudo distance between the positions of

(Operation) Next, the operation of the GPS navigation device configured as shown in FIG. 1 will be explained with reference to these drawings.

Radio waves from the GPS satellites are captured by a GPS receiver antenna 6 and sent to the GPS receiver 1. GPS
Receiver 1 amplifies and demodulates the GPS signal to detect satellite position data and pseudorange data. If the number of receivable satellites is 3 or more, the reception position calculator 3
The received position is calculated from the satellite position data and pseudorange data from the GPS receiver 1, and the result is displayed as a numerical value or a track on the position display 4. However, while the car is driving in a city, etc., it is not possible to receive radio waves from three satellites at the same time due to a shield 10 such as a building (Figs. 3 and 4), and as shown in the reception situation of satellite radio waves in Fig. When receiving radio waves from two satellites intermittently, the pseudosatellite position calculator 2 calculates the moving direction and moving distance obtained from the direction data from the magnetic compass 7 and the distance data from the distance meter 8. The pseudosatellite position at time t2 is calculated by adding it to the satellite position data at time t1 immediately before the reception of radio waves from satellite 3 in FIG. 3 is interrupted. The reception position calculator 3 is as shown in Figure 3.
Satellite 1 at time t2 from GPS receiver 1,
The received data of the satellite 2, that is, the pseudorange data and the satellite position data, and the pseudorange data of the satellite 3 at time t1, which is used as the pseudorange of the satellite 3 at time t2, and the pseudosatellite position data of the satellite 3 at time t2 are used to calculate the satellite 3. The reception position at time t2 is calculated even if the reception is interrupted. The position can then be displayed numerically on the position display 4 or as a track on a map.

Although Figures 3 and 4 show the case where the radio waves of Satellite 3 are blocked, it is also possible to measure the position of the car even if the radio waves of Satellite 2 and Satellite 3 are blocked at the same time. That is clear.

As shown in the positioning error graph in Figure 2b, the period from time t1 to t2, when it is impossible to receive three or more satellite radio waves, is calculated using the direction data from the magnetic compass, distance data from the range finder, and Time t1
When an estimated position is calculated using the received position data at , the positioning error increases with time, as shown by the estimated position error in FIG. 2b. However, if the received position of the car is calculated as described above, the positioning error is reduced compared to the conventional estimated position error, as shown in Figure _2b , and it hardly increases over time. It's not easy.

(Effects of the Invention) As is clear from the above description, the present invention is effective when installing a GPS receiver in a car and using it in urban areas where there are many shielding objects such as buildings. Therefore, continuous position measurement is not possible, and even if continuous position measurement is possible using the estimated position based on the direction data from the magnetic compass and the distance data from the distance meter, good positioning accuracy cannot be expected. By calculating the pseudo satellite position data using the satellite position data immediately before reception interruption in addition to the data and distance data, the number of received satellites can be reduced to 1.
Position measurement can be performed with high accuracy even in the case of one or two.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of one embodiment of the present invention, and FIG.
In the figure, a shows the reception status of satellite radio waves, b shows the positioning error curve, Fig. 3 is an explanatory diagram of a car receiving radio waves from a satellite, and Fig. 4 shows the case of receiving radio waves from a satellite according to the present invention. FIG. 1... GPS receiver, 2... Pseudo satellite position calculator, 3... Reception position calculator, 4... Position indicator,
5...Car, 6...GPS receiver antenna,
7... Magnetic compass, 8... Distance meter, 9... Shielding object, 10... Measurement position.

Claims (1)

[Claims] 1 A GPS receiver that receives radio waves from a GPS satellite and outputs position data of the GPS satellite and pseudo distance data between the GPS satellite and the vehicle, and the GPS
From the point when the receiver is unable to receive radio waves from three or more satellites at the same time due to obstructions, the vehicle's direction of travel is determined based on the previous satellite position data while reception is interrupted. Pseudo satellite position data is generated as a satellite that can be received in a pseudo manner using the moving direction and distance of the vehicle obtained from the direction data from the magnetic direction meter to be detected and the distance data from the distance meter that detects the number of rotations of the vehicle. The number of receivable satellites is 3 or more by inputting the pseudolite position calculator to calculate and output, the pseudorange data from the GPS receiver, the satellite position data, and the pseudolite position data from the pseudolite position calculator. The position is calculated by using the pseudorange data and the satellite position data at the time of It consists of a received position calculator that calculates the position by GPS satellite navigation when used together, and a position indicator that displays the positioning results from the received position calculator as a numerical display or a track on a map. A GPS navigation device characterized by measuring position continuously without interruption.